The disclosure relates to the field of designing and making of filter assemblies used to filter fluids, including fluids flowing in hydraulic motors or apparatuses, and other fluid flow applications.
Such filter assemblies consist of a filter element or filter body, comprising a vessel and a cover, within which there is disposed a filter cartridge including a filtering medium, generally cylindrical in shape and surrounding a tubular cavity, the filtering medium being possibly made for example of paper, cardboard or again felt or another porous material, such as a synthetic or non-synthetic, woven or non-woven material. The filter cartridge also comprises two end flanges delimiting the filtering medium.
Such filter cartridges generally cooperate with a tube, in particular a center tube, which may or may not be fixedly joined to the flanges. The external diameter of the tube is close to the internal diameter of the tubular cavity surrounded by the filtering medium, so as to limit the deformations of the medium caused by the pressure exerted within the filter assembly.
The end flanges are formed by a first flange, which may consist of an upper flange, and a second flange, which may consist of a lower flange. The role of the flanges is to participate in the tight sealing of the filter cartridge and to enable the fixed joining of the filter cartridge to the permanent part of the filter assembly.
The filter cartridge is, in this type of filter assembly, generally removable or detachable so it can be replaced at the end of its service life by a new filter cartridge.
The operator uncaps the cover of the filter assembly and then grasps the filter cartridge, removes it from the vessel and replaces it with a new filter cartridge. In addition, the operator changes the gasket between the cover and the vessel. These operations cause the operator to handle several elements which are liable to get soiled on parts that would then come into contact with the clean, filtered fluid, after the filtering medium, so that the contamination is no longer stopped by the filter but goes directly to the motor for example. Besides, these numerous operations give rise to substantial labor time for the maintenance of the filter assembly.
The disclosure provides a filter assembly that is clean, fast and easy to maintain during the replacement of the filter cartridge.
The disclosure provides a filter assembly that has a limited number of parts.
The disclosure provides a filter assembly for which it is known with certainty that, when it is closed, it includes a filter cartridge.
The disclosure provides a filter assembly including:                a filter element including a vessel and a cover,        a tube, in particular a central tube, within the filter element extending along a longitudinal axis,        a removable filter cartridge housed in the filter element and comprising a first flange, a second flange, and a filtering medium extending between the first and second flanges and having a tubular hollow space to surround the tube.        
In one embodiment, the first flange of the filter cartridge at least partially forms the cover of the filter element.
The first flange at least partially closes the filter assembly. The filter cartridge therefore includes a part, namely at least one part of the first flange, partially forming an external wall of the filter assembly.
The replacement of a filter cartridge is relatively easy. Indeed, removing the cover results in removing the filter cartridge to which it is fixedly joined.
This also improves the cleanliness of the maintenance of the filter assembly.
In another embodiment, it is not possible to overlook the operation for positioning the filter cartridge, since the first flange at least partially forms the cover of the filter assembly.
The filter gasket requires no handling since it is fixedly joined to the first flange, and therefore to the filter cartridge that is removed, and to the new filter cartridge that is positioned.
According to one embodiment, the first flange is configured to cooperate by force with the vessel so as to close the filter element in a tightly sealed manner.
As a variant, or additionally, the first flange can rest on an upper edge of the vessel.
The free end portion of the vessel can take a substantially cylindrical form and the first flange a substantially circular external outline, configured to cooperate with the vessel in order to ensure tightly-sealed closure of the filter assembly.
The filter assembly may include a holder for holding the first flange on the vessel, especially configured to prevent the detachment of the first flange from the vessel and/or configured to enable the filter cartridge to be held fixedly in the vessel.
The holder can be distinct from the first flange and possibly from the filter cartridge. As a variant, the holder can be fixedly attached or fixed to the filter cartridge.
The holder enables the cover to be held firmly on the vessel, to ensure the safety of the closure of the filter assembly.
The tube can be fixed removably relative to the filter element, especially by screwing or by being clipped on or the like. The tube can be fixed by screwing a lower threaded part of the tube on to a corresponding threaded part of the vessel.
In this case, the first flange can for example include an aperture, in particular a central aperture, and the tube can include an upper extension passing through the aperture of the first flange and cooperating in a tightly sealed manner with the aperture, for example by a gasket. The upper extension is then configured to abut against an external face of the first flange and form the holder.
In this case, the filter cartridge can be replaced as follows. The removable tube is withdrawn. Thus, the filter cartridge is released and can then be withdrawn to be replaced by a new one and then the filter assembly is closed in putting the tube back into place.
The filter assembly can include a closing ring fixedly joined externally with an end portion of the vessel while at the same time being at least partially mobile, especially in rotation, relatively to the vessel and forming the holder.
In this case, the closing ring is configured so that, by partial rotation relatively to the vessel while remaining fixed to it, it can pass from a first position enabling the filter cartridge to be withdrawn from the vessel or enabling the filter cartridge to be positioned in the vessel to a second position preventing the filter cartridge from being withdrawn from the vessel or preventing the filter cartridge from being positioned in the vessel, and vice versa.
In the latter case, a peripheral shoulder of the first flange can for example have a plurality of fins, e.g. four fins. For its part the closing ring may, in a retaining shoulder extending diametrically inwards, include a plurality of notches configured to cooperate with the fins of the closing ring so as to make the closing ring pass, by partial rotation of the closing ring, from the first position in which the notches and the fins are superimposed to the second position in which the notches and the fins are positioned so as to be offset without superimposition. The retaining shoulder can be in contact with the first flange in the tightly-sealed closed position of the filter assembly.
The closing ring can be removable and can be configured in such a way that, when it is fixedly joined to the vessel in a holding position, it prevents any withdrawal of the filter cartridge.
The holding position can be one that prevents any movement of the filter cartridge in relation to the rest of the filter assembly. For example, if the closing ring is fixedly joined to the vessel by screwing, the holding position is a screwing position with a high tightening torque, for example torque greater than 25 Nm, so as to provide for the secured closing of the filter assembly.
The closing ring can be fixed by screwing to the vessel, the vessel including an external thread and the closing ring including a corresponding internal thread.
The first flange can be provided, in proximity to its periphery, with at least one elastic clip-on tab. The elastic clip-on tab or tabs can help in the mounting and/or dismounting of the filter cartridge.
The first flange can be equipped, on an external face, with a removable or non-removable grip, configured to enable or facilitate the grasping of the filter cartridge.
The filter assembly can comprise at least one ring gasket cooperating with the first flange to provide for the tight sealing of the closure between the vessel and the first flange.
In this case, the gasket is fixedly joined to the first flange and therefore to the filter cartridge, thus enabling it to be changed by the replacement of the filter cartridge.
In this case, the first flange may for example present a peripheral shoulder having a ring-shaped peripheral housing to house the gasket.
As a variant, the first flange may have a peripheral shoulder having a peripheral rib and the gasket may be configured to cooperate with the peripheral rib, for example by being fitted on to the peripheral rib.
The gasket can be configured, when there is a closing ring, to provide for tight sealing between the closing ring, the vessel and the first flange.